Thermophysical Properties of Metal-Insulator Transition Materials During Phase Transition for Thermal Control Devices

Abstract This study reports on the fabrication of metal-insulator transition materials and measurement of the temperature dependency of their thermophysical properties, namely, specific heat, thermal conductivity, and total hemispherical emittance to evaluate the potential of these materials as multifunctional thermal control devices. Perovskite-type manganese oxide, La0.8Sr0.2MnO3 (LSMO) and La0.8Pb0.2MnO3 (LPMO), and vanadium dioxide (VO2) are selected as candidate materials. LSMO and LPMO are prepared using the solution combustion and simple sintering methods, and VO2 is prepared using the spark plasma sintering method. The phase transition temperatures, specific heat capacities, and heat storage capabilities during the phase transition of these materials are measured via differential scanning calorimetry. The thermal conductivities are measured via AC calorimetric method. The total hemispherical emittances are measured using the steady-state calorimetric method. Results show that VO2 has the highest heat storage capability during phase transition. The large change in the total hemispherical emittances of LSMO and LPMO and the large change in the thermal conductivity of VO2 before and after phase transition are confirmed. Moreover, tungsten-doped vanadium dioxide (VWO2) is fabricated to reduce the phase transition temperature to much lower than that of VO2, and the measurement results of its thermophysical properties are also presented.